Regex格式没有按预期工作

我有以下扩展方法:

/*
* text.Format("hello", "no") --> Replaces all appearances of "{hello}" with "no"
*
* For example, if text would have been "{hello} how are you?", the method would have returned "no how are you?"
*/
public static StringBuilder CustomFormat(this StringBuilder text, string name, string value)
{
     return text.Replace(String.Format("{{{0}}}", name), value);
}
/*
*  text.FormatUsingRegex("(?'hello'[A-Z][a-z]{3})", "Mamma mia") --> Replaces the text with the found matching group in the input
*
* For example if text would have been "{hello}oth", the method would have returned "Mammoth"
*/
public static StringBuilder FormatUsingRegex(this StringBuilder text, string regexString, string input)
{
     Regex regex = new Regex(regexString);
     List<string> groupNames = regex.GetGroupNames().ToList();
     Match match = regex.Match(input);
     groupNames.ForEach(groupName => text.CustomFormat(groupName, match.Groups[groupName].Value));
     return text;
}

我用以下参数调用方法:

 StringBuilder text = new StringBuilder("/index.aspx?xmlFilePath={xmlFilePath}");
 text.FormatUsingRegex("(f=(?'xmlFilePath'.*))?","http://localhost:24674/preview/f=MCicero_temppreview.xml");

我希望text最终会像/index.aspx?xmlFilePath=MCicero_temppreview.xml一样，但我得到了/index.aspx?xmlFilePath=，好像组与输入不匹配。

我在Regex101中尝试了这个正则表达式和输入，它似乎工作得很好。

这里可能发生了什么?